Method for operating an electronic vapour inhaler

ABSTRACT

A method is provided for operating an electronic vapour inhaler (10) comprising an induction heating arrangement (34), the induction heating arrangement (34) comprising an induction coil (36) for generating an alternating electromagnetic field to heat an induction heatable element (28) and thereby heat a non-liquid flavour-release medium (30). The method comprises intermittently energising the induction coil (36) to generate an intermittent alternating electromagnetic field which provides pulsed heating and cooling of the induction heatable element (28).

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a national phase entry under 35 U.S.C. § 371of International Application No. PCT/GB2016/053168, filed Oct. 13, 2016,published in English, which claims priority to Great Britain ApplicationNo. 1518244.7 filed Oct. 15, 2015, the disclosures of which areincorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates generally to electronic vapour inhalersand more particularly to a method for operating an electronic vapourinhaler in which a non-liquid flavour-release medium is heated toproduce a vapour for inhalation by a user.

TECHNICAL BACKGROUND

The use of electronic vapour inhalers (also known as electroniccigarettes, e-cigarettes and personal vaporisers), which can be used asan alternative to conventional smoking articles such as lit-endcigarettes, cigars, and pipes, is becoming increasingly popular andwidespread. The most commonly used electronic vapour inhalers areusually battery powered and use a resistance heating element to heat andatomise a liquid containing nicotine, to produce a nicotine-containingvapour which can be inhaled by a user. The vapour is inhaled through amouthpiece to deliver nicotine to the lungs, and vapour exhaled by theuser generally mimics the appearance of smoke from a conventionalsmoking article. Although inhalation of the vapour creates a physicalsensation which is similar to conventional smoking, harmful chemicalssuch as carbon dioxide and tar are not produced or inhaled because thereis no combustion.

In the conventional e-cigarettes described above, the liquid is wickedonto the resistance heating element. This provides rapid atomisation ofthe liquid, and hence rapid start-up of the e-cigarette followingactivation by a user, but the flavour can be sub-optimal. A conventionaltobacco material or other non-liquid flavour-release medium can be usedinstead of a liquid in order to provide improved flavourcharacteristics. However, the start-up period (in other words the “timeto first puff”) after initial activation of the e-cigarette by the useris longer because more time is needed to heat the tobacco material orother non-liquid flavour-release medium to a temperature at which asatisfactory amount of vapour is produced. This is due to the higherthermal mass of the resistance heating element which has a slowresponse.

WO 2014/102091 proposes a solution to this problem by providing aresistance-heated aerosol-generating device which has three heatingphases. In particular, there is a first phase during which thetemperature of the heating element is raised from ambient temperature toa first temperature, a second phase during which the temperature of theheating element drops below the first temperature and a third phaseduring which the temperature of the heating element increases again. Thefirst phase is a high-temperature phase in which the temperature of theheating element is raised as close as possible to the combustiontemperature of an aerosol-forming substrate used in the device. Thesecond phase is a lower-temperature phase in which the temperature ofthe heating element is reduced to provide a continued delivery ofaerosol to the user. The third phase is also a high-temperature phasewhich aims to provide a continued delivery of aerosol to the user as theaerosol-forming substrate becomes depleted.

WO 2014/102091 indicates that the preferred temperature range for thefirst phase is between 340° C. and 400° C., and provides specificexamples of 360° C. for 45 seconds, 340° C. for 60 seconds and 380° C.for 30 seconds. WO 2014/102091 explains that the maximum operatingtemperature of any of the first, second and third phases is preferablyno more than approximately 380° C., which is stated to be the combustiontemperature for undesirable compounds that are present in conventional,lit-end cigarettes. It is, therefore, apparent that the temperature ofthe heating element during the first phase is very high and close to themaximum allowable temperature for a relatively extended period. This maycause charring of the aerosol-forming substrate and would be highlyundesirable as it produces an aerosol with an unpleasant or ‘off’ taste.This may also begin to generate the undesirable compounds that aregenerated in conventional, lit-end cigarettes, as a result ofcombustion. Furthermore, even at the very high temperatures described inWO 2014/102091, the start-up period is still unacceptably longespecially when compared to the instantaneous availability of a lit-endcigarette or an e-cigarette which heats and atomises a liquid.

There is, therefore, a need for an electronic vapour inhaler whichovercomes these difficulties.

SUMMARY OF THE DISCLOSURE

According to a first aspect of the present disclosure, there is provideda method for operating an electronic vapour inhaler comprising aninduction heating arrangement, the induction heating arrangementcomprising an induction coil for generating an alternatingelectromagnetic field to heat an induction heatable element and therebyheat a non-liquid flavour-release medium, the method comprisingintermittently energising the induction coil to generate an intermittentalternating electromagnetic field which provides pulsed heating andcooling of the induction heatable element.

According to a second aspect of the present disclosure, there isprovided an electronic vapour inhaler comprising:

-   -   an induction heating arrangement, the induction heating        arrangement comprising an induction coil for generating an        alternating electromagnetic field to heat an induction heatable        element and thereby heat a non-liquid flavour-release medium;        and    -   a control arrangement for controlling the operation of the        induction heating arrangement to intermittently energise the        induction coil to generate an intermittent alternating        electromagnetic field which provides pulsed heating and cooling        of the induction heatable element.

The non-liquid flavour-release medium may comprise any material orcombination of materials which can be heated to release a vapour forinhalation by a user. The non-liquid flavour-release medium is a drymaterial and can be easily handled. The non-liquid flavour-releasemedium may be tobacco or a tobacco material or a dry herbal material.The non-liquid flavour-release medium could take any suitable form,including fine pieces or pellets or a fibrous form. The non-liquidflavour-release medium may be impregnated with a vapour-forming mediumsuch as propylene glycol, glycerol or a combination thereof.

The induction heatable element has a low thermal mass and can,therefore, be heated rapidly in the presence of the alternatingelectromagnetic field generated by the induction coil of the inductionheating arrangement. The induction heatable element may, for example, beheated from ambient temperature to approximately 250° C. in 0.2 seconds.The low thermal mass also allows the induction heatable element torapidly cool in the absence of the alternating electromagnetic field, asthe heat energy is transferred into the surrounding non-liquidflavour-release medium. By intermittently energising the induction coilto provide an intermittent alternating electromagnetic field, and henceintermittent or pulsed heating and cooling of the induction heatableelement, a large amount of energy can be delivered to the inductionheatable element without burning or overheating the non-liquidflavour-release medium. As a result of heat transfer from the inductionheatable element to the non-liquid flavour-release medium, for exampleby conduction, radiation and convection, the non-liquid flavour-releasemedium, or at least one or more localised regions thereof, can berapidly heated to a temperature within an operating temperature range atwhich a vapour is generated having suitable characteristics (includingflavour and aroma) for inhalation by a user. The intermittent or pulsedheating and cooling of the induction heatable element combined with thelow thermal mass of the induction heatable element ensures that thenon-liquid flavour-release medium does not reach a temperature above theoperating temperature range at which overheating, burning or charringoccur and enables the non-liquid flavour-release medium to be heatedrapidly to a temperature in the operating temperature range.

The method may comprise varying the pulse frequency of the powersupplied to the induction coil to intermittently energise the inductioncoil. The method may comprise varying the pulse amplitude of the powersupplied to the induction coil to intermittently energise the inductioncoil. The method may comprise varying the duty cycle of the powersupplied to the induction coil to intermittently energise the inductioncoil. Controlling the pulse frequency and/or the pulse amplitude and/orthe duty cycle provides control over the pulsed heating and cooling ofthe induction heatable element and therefore allows the operatingtemperature of the non-liquid flavour-release medium to be controlled.

The pulsed heating and cooling of the induction heatable element mayheat the non-liquid flavour-release medium to an operating temperaturein an operating temperature range having a lower limit of between 150°C. and 200° C. and an upper limit of between 200° C. and 250° C.Typically, the operating temperature range is between 180° C. and 240°C. In the case where the non-liquid flavour-release medium is a tobaccomaterial which might typically have a combustion temperature in theregion of 380° C., it will be apparent that the upper limit of theoperating temperature range is substantially lower than the combustiontemperature. As a consequence, charring and burning of the tobaccomaterial is avoided and this ensures that the vapour generated byheating the tobacco material has optimum characteristics.

The method may comprise a first operating phase in which the inductioncoil is intermittently energised to generate an intermittent alternatingelectromagnetic field which provides pulsed heating and cooling of theinduction heatable element to heat the non-liquid flavour-release mediumto a temperature in the operating temperature range. The first operatingphase may have a duration which typically does not exceed 10 seconds.More typically, the duration does not exceed 5 seconds. Thus, it will beapparent that the start-up time (in other words the “time to firstpuff”) is significantly less than that of the aerosol-generating devicedescribed in WO 2014/102091.

The method may comprise a second operating phase in which the inductioncoil is intermittently energised to generate an intermittent alternatingelectromagnetic field which provides pulsed heating and cooling of theinduction heatable element to maintain the average temperature of thenon-liquid flavour-release medium within the operating temperaturerange. The strength of the alternating electromagnetic field istypically lower during the second operating phase than during the firstoperating phase. This is possible because the component parts of theelectronic vapour inhaler have already been heated up during the firstoperating phase and because the amount of moisture and vapour-formingmedium in the non-liquid flavour-release medium has decreased. Thus,less energy is needed to maintain the average temperature of thenon-liquid flavour-release medium within the operating temperaturerange.

During the second operating phase, the induction coil may beintermittently energised based on user demand. Such an implementation ispossible again because of the low thermal mass and rapid heating andcooling characteristics of the induction heatable element which enablethe induction heatable element to be rapidly heated in the presence ofthe electromagnetic field and to rapidly cool in the absence of theelectromagnetic field. The user demand may be detected by any suitablemeans which are indicative that inhalation by a user of the electronicvapour inhaler is taking place or is imminent. For example, theelectronic vapour inhaler could include an accelerometer to detectmovement thereof by a user towards the lips, a capacitive sensor todetect contact with the lips or a flowmeter or flow-switch to detectactual inhalation by a user.

The induction coil may be intermittently energised according to apredetermined heating profile. The predetermined heating profile may beselectable by a user, for example in real-time via a wireless (e.g.Bluetooth®) communication interface. The predetermined heating profilemay be selected automatically, for example based on a detectedcharacteristic which is related to the non-liquid flavour-releasemedium.

The electronic vapour inhaler may comprise a plurality of inductionheatable elements. The number of induction heatable elements can beselected to provide for optimum heating of the non-liquidflavour-release medium.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is diagrammatic cross-sectional view of one example of anelectronic vapour inhaler which can be operated in accordance with themethod of the present disclosure;

FIG. 2a is a schematic illustration of a pulsed heating profile in aninduction heatable element illustrating the intermittent heating andcooling of the induction heatable element;

FIG. 2b is a schematic illustration of the intermittent operation of aninduction coil which generates the pulsed heating profile of FIG. 2a ;and

FIG. 2c is a schematic illustration of the average operating temperatureof a non-liquid flavour-release medium provided by the pulsed heatingprofile of FIG. 2 a.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the present disclosure will now be described by way ofexample only and with reference to the accompanying drawings.

Referring initially to FIG. 1, an electronic vapour inhaler 10 comprisesa generally elongate housing 12 having a proximal end 14 and a distalend 16. The electronic vapour inhaler 10 includes a mouthpiece 18 at theproximal end 14 through which a user can inhale vapour generated byheating a non-liquid flavour-release medium 30. The electronic vapourinhaler 10 includes a control arrangement 20, e.g. in the form of amicroprocessor, and a power source 22 in the form of one or morebatteries which could, for example, be inductively rechargeable.

The housing 12 includes a chamber 24 containing the non-liquidflavour-release medium 30. The chamber 24 is located at the proximal end14 of the housing 12 adjacent to the mouthpiece 18, but this is notstrictly necessary and it could be located at any suitable positionbetween the proximal end 14 and the distal end 16. In the illustratedembodiment, the chamber 24 is formed in the housing 12 and is accessedby removing a cover 25, with which the mouthpiece 18 is integrallyformed, from the proximal end 14 of the housing 12. In alternativeembodiments, the chamber 24 could itself be formed as a removablecomponent and could be accessed by removing the component from thehousing 12.

In the illustrated embodiment, the non-liquid flavour-release medium 30is embodied as a cartridge 26 which can be removably inserted into thechamber 24. The cartridge 26 comprises an elongate induction heatableelement 28 and the non-liquid flavour-release medium 30 which can beadhered or otherwise fixed to the surface of the induction heatableelement 28. It is to be understood that the embodiment of the electronicvapour inhaler 10 illustrated in FIG. 1 is provided merely as an exampleto facilitate the description of the method of operation according tothe present disclosure. Other arrangements are entirely within the scopeof the present disclosure, for example arrangements which use aplurality of induction heatable elements, in which the or each inductionheatable element has a different geometry, in which the cartridge 26 isreplaced by an air-permeable capsule containing the non-liquidflavour-release medium 30 and one or more induction heatable elements28, etc.

The non-liquid flavour-release medium 30 typically comprises tobaccomaterial, but other non-liquid flavour-release products can be used. Thenon-liquid flavour-release medium 30 is typically impregnated with avapour-forming medium, such as propylene glycol, glycerol or acombination of both, and when heated to a temperature within anoperating temperature range produces a vapour for inhalation by a userthrough the mouthpiece 18 of the electronic vapour inhaler 10.

The electronic vapour inhaler 10 includes an induction heatingarrangement 34 comprising an induction coil 36 which can be energised bythe power source 22. As will be understood by those skilled in the art,when the induction coil 36 is energised, an alternating electromagneticfield is produced which generates eddy currents in the inductionheatable element 28 causing it to heat up. The heat is then transferredfrom the induction heatable element 28 to the non-liquid flavour-releasemedium 30, for example by conduction, radiation and convection, and thenon-liquid flavour-release medium 30 is thereby heated. The operation ofthe induction heating arrangement 34 is controlled by the controlarrangement 20 and will now be described in further detail.

Referring to FIGS. 2a to 2c , upon activation of the electronic vapourinhaler 10 by a user, the control arrangement 20 causes the inductionheating arrangement 34, and more particularly the induction coil 36, tobe intermittently energised by the power source 22. This intermittent,or pulsed, operation is represented by the ‘on’ and ‘off’ pulses whichare shown clearly in FIG. 2b . This intermittent, or pulsed, operationcauses the induction coil 36 to generate an intermittent, or pulsed,alternating electromagnetic field which in turn provides pulsed heatingand cooling of the induction heatable element 28. The pulsed heating andcooling of the induction heatable element 28 is clearly shown in FIG. 2awhich illustrates the varying temperature over time of the inductionheatable element 28. The characteristics of the pulsed heating andcooling can be influenced by controlling the pulse frequency of thepower supplied to the induction coil 36 (in other words the numberand/or length of pulses in a given time period), for example as shown inFIG. 2b . Alternatively or in addition, the characteristics of thepulsed heating and cooling can be influenced by controlling the pulseamplitude of the power supplied to the induction coil 36 and/or byvarying the duty cycle of the power supplied to the induction coil 36.

The pulsed heating and cooling of the induction heatable element 28 asdepicted in FIG. 2a rapidly heats the non-liquid flavour-release medium30, and especially localised regions thereof, from ambient temperatureT_(A) to an operating temperature T₁ (see FIG. 2c ) which is typicallybetween 180° C. and 220° C. This operating temperature T₁ issignificantly lower than the combustion temperature of typical tobaccomaterial (approx. 380° C.) and ensures that there is no overheating,charring or burning of the tobacco material.

The control arrangement 20 can be configured to maintain the pulsedheating and cooling of the induction heatable element 28 (byintermittently energising the induction coil 36) throughout the periodof use of the electronic vapour inhaler 10 until such time as it isdeactivated by the user. This deactivation may, for example, occur whenthe constituents of the non-liquid flavour-release medium 30 have beendepleted and the resulting vapour no longer has acceptablecharacteristics such as flavour and aroma.

Referring to FIG. 2c , the pulsed heating and cooling of the inductionheatable element 28 to achieve the operating temperature T₁ occursduring a first operating phase 40 following activation of the electronicvapour inhaler 10. This first operating phase 40 can be considered torepresent a start-up phase in which initial heating of the non-liquidflavour-release medium 30 occurs to make the electronic vapour inhaler10 ready for use and, thus, in which the temperature of at leastlocalised regions of the non-liquid flavour-release medium 30 isincreased from ambient temperature T_(A) to a temperature at which avapour suitable for inhalation by a user is generated. After the end ofthe first operating phase 40, the average temperature of the non-liquidflavour-release medium 30 continues to increase at the start of a secondoperating phase 42 until it reaches a higher temperature T₂. A typicalduration of the first operating phase 40 is less than 10 seconds, andmore typically in the region of 5 seconds or less. It will beappreciated that this heating is much more rapid than the heatingprovided during the first phase of operation of the device described inWO 2014/102091 (between 30 and 60 seconds) such that the start-up timeis more rapid and, hence, the ‘time to first puff’ is as short aspossible.

During the second operating phase 42, the control arrangement 20 canreduce the energy supplied by the power source 22 to the induction coil36 to reduce the strength of the electromagnetic field and to therebyreduce the temperature of the induction heatable element 28. This ispossible because the component parts of the electronic vapour inhaler 10have been heated during the first operating phase 40 and because theamount of moisture and vapour-forming medium in the non-liquidflavour-release medium 30 have decreased. Thus, the non-liquidflavour-release medium 30 can be maintained at the average operatingtemperature T₂ even with a lower energy input into the induction coil36. In the second operating phase 42 illustrated in FIG. 2c , theoperating temperature T₂ of the non-liquid flavour-release medium 30 isshown to remain relatively constant. However, the operating temperatureof the non-liquid flavour-release medium 30 could increase or decreaseduring the second operating phase 42 to ensure that an acceptableflavour and aroma continues to be delivered to the user.

In one embodiment, during the second operating phase 42 the controlarrangement 20 controls the amount of energy transferred to thenon-liquid flavour-release medium 30, by varying the pulse ratio of thepower source 22 to the induction coil 36, based on user demand. Moreparticularly, the electronic vapour inhaler 10 can comprise means fordetecting when inhalation by a user is imminent or actually takingplace. For example, the electronic vapour inhaler 10 could comprise anaccelerometer for detecting movement by a user towards their lips, acapacitive sensor (so-called lip detector) fitted to the mouthpiece 18to detect when the mouthpiece comes into contact with a user's lips, ora flowmeter/flow-switch to detect when a user is actually inhalingthrough the mouthpiece 18. It will be understood that these detectionmeans are merely provided by way of example and that other detectionmeans are entirely within the scope of the present disclosure.

In this embodiment, when the control arrangement 20 receives a signalfrom the detection means indicating that inhalation by a user isimminent or actually taking place, the control arrangement 20 increasesthe energy supplied by the power source 22 to the induction coil 36.This raises the temperature of the induction heatable element 28 and inturn increases the temperature of the non-liquid flavour-release medium30. Once again, the control arrangement 20 is configured to cause theinduction coil 36 to be intermittently energised by the power source 22upon receipt of a signal from the detection means. This causes theinduction coil 36 to generate an intermittent alternatingelectromagnetic field which in turn provides pulsed heating and coolingof the induction heatable element 28.

If desired, the induction coil 36 can be intermittently energised(during the first operating phase 40 and/or the second operating phase42) according to a predetermined heating profile. The predeterminedheating profile could be selected by a user, for example to provide forhigher or lower operating temperatures depending on the preference ofthe user and/or the characteristics of the non-liquid flavour-releasemedium 30. Alternatively or in addition, the predetermined heatingprofile could be selected automatically based on a detectedcharacteristic which is related to the non-liquid flavour-release medium30.

Although exemplary embodiments have been described in the precedingparagraphs, it should be understood that various modifications may bemade to those embodiments without departing from the scope of theappended claims. Thus, the breadth and scope of the claims should not belimited to the above-described exemplary embodiments. Each featuredisclosed in the specification, including the claims and drawings, maybe replaced by alternative features serving the same, equivalent orsimilar purposes, unless expressly stated otherwise.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise”, “comprising”, and thelike, are to be construed in an inclusive as opposed to an exclusive orexhaustive sense; that is to say, in the sense of “including, but notlimited to”.

Any combination of the above-described features in all possiblevariations thereof is encompassed by the present invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

The invention claimed is:
 1. A method for operating an electronic vapourinhaler comprising an induction heating arrangement, the inductionheating arrangement comprising an induction coil for generating analternating electromagnetic field to heat an induction heatable elementand thereby heat a non-liquid flavour-release medium, the methodcomprising intermittently energising the induction coil with pulses ofvarying length during a first operating phase to generate anintermittent alternating electromagnetic field which provides pulsedheating and cooling of the induction heatable element.
 2. An operatingmethod according to claim 1, wherein the method comprises varying pulsefrequency of the power supplied to the induction coil.
 3. An operatingmethod according to claim 1, wherein the method comprises varying pulseamplitude of the power supplied to the induction coil.
 4. An operatingmethod according to claim 1, wherein the method comprises varying a dutycycle of the power supplied to the induction coil.
 5. An operatingmethod according to claim 1, wherein the pulsed heating and cooling ofthe induction heatable element heats the non-liquid flavour-releasemedium to an operating temperature in an operating temperature rangehaving a lower limit of between 150° C. and 200° C. and an upper limitof between 200° C. and 250° C.
 6. An operating method according to claim5, wherein the operating temperature range is between 180° C. and 240°C.
 7. An operating method according to claim 5, wherein during the firstoperating phase, the induction coil is intermittently energised togenerate an intermittent alternating electromagnetic field whichprovides pulsed heating and cooling of the induction heatable element toheat the non-liquid flavour-release medium to a temperature in theoperating temperature range.
 8. An operating method according to claim7, wherein the first operating phase has a predetermined duration.
 9. Anoperating method according to claim 8, wherein the duration of the firstoperating phase does not exceed 10 seconds.
 10. An operating methodaccording to claim 9, wherein the duration does not exceed 5 seconds.11. An operating method according to claim 7, wherein the method furthercomprises a second operating phase in which the induction coil isintermittently energised to generate an intermittent alternatingelectromagnetic field which provides pulsed heating and cooling of theinduction heatable element to maintain the average temperature of thenon-liquid flavour-release medium within the operating temperaturerange.
 12. An operating method according to claim 11, wherein thestrength of the alternating electromagnetic field is lower during thesecond operating phase than during the first operating phase.
 13. Anoperating method according to claim 11, wherein, during the secondoperating phase, the induction coil is intermittently energised based onuser demand.
 14. An operating method according to claim 1, wherein theinduction coil is intermittently energised according to a predeterminedheating profile.
 15. An operating method according to claim 14, whereinthe predetermined heating profile is selectable by a user.
 16. Anoperating method according to claim 15, wherein the predeterminedheating profile is selected automatically based on a detectedcharacteristic which is related to the non-liquid flavour-releasemedium.
 17. A method for operating an electronic vapour inhalercomprising an induction heating arrangement, the induction heatingarrangement comprising an induction coil for generating an alternatingelectromagnetic field to heat an induction heatable element and therebyheat a non-liquid flavour-release medium, the method comprisingintermittently energising the induction coil to generate an intermittentalternating electromagnetic field which provides pulsed heating andcooling of the induction heatable element to heat the non-liquid flavourrelease medium to an operating temperature in an operating temperaturerange having a lower limit of between 150° C. and 200° C. and an upperlimit of between 200° C. and 250° C., wherein the method comprises: afirst operating phase in which the induction coil is intermittentlyenergised to generate an intermittent alternating electromagnetic fieldwhich provides pulsed heating and cooling of the induction heatableelement to heat the non-liquid flavour-release medium to a temperaturein the operating range; a second operating phase in which the inductioncoil is intermittently energised to generate an intermittent alternatingelectromagnetic field which provides pulsed heating and cooling of theinduction heatable element to maintain the average temperature of thenon-liquid flavour-release medium within the operating range, whereinduring the second operating phase, the induction coil is intermittentlyenergised based on user demand to increase the temperature of theinduction heatable element.
 18. The method of claim 17, wherein userdemand is determined by an accelerometer or a capacitive sensor prior toinhalation by a user.